#include<fstream.h>

long m,a,exp,p,r,l;

long fact(long x)
{
 long b=5,exp=0;
 while(x>=b)
 {
  exp+=x/b;
  b*=5; 
  }
 return exp;
 }

int main()
{
 ifstream f("fact.in");
 ofstream g("fact.out");
 f>>p;
 a=1;exp=0;
 while(exp<p)
  {
   a<<=1;
   exp=fact(a);
   }
 a-=5;
 while(fact(a)>p)a-=5;
 g<<a-(a%5);
 return 0;
 }